Question

A specific phosphatase is associated with PDH complex. For the situation below, indicate whether the phosphatase will be activated or deactivated with a short reason? i) In presence of high levels of epinephrine and Ca 2+ in muscle. ii) in presence of high levels of insulin in liver and adipose tissue.

Answer 1

PDH is regulated by a specific PDH phosphatase

In the presence of high level of epinephrine and Ca ²⁺ in muscles, the PDH phosphatase will be inactive and thus the PDH complex will be inactive.

This is because as epinephrine is a fight or flight hormone and as the epinephrine level increases the cell will need more and instant energy instead of following the PDH complex pathway the cell will use the lactate pathway for generation of energy. and during the epinephrine signaling tough GPCR pathway there will be an increase in Ca ²⁺ level.

In presence of high level of insulin in liver and adipose tissue, the phosphatase enzyme will be activated and thus PDH complex will also be activated.

This is because in the presence of high insulin the cells need to form and store energy. So, the cell will utilize the PDH- Kreb cycle pathway followed by Oxidative phosphorylation.